Campylobacter jejuni is susceptible to a variety of environmental conditions that make it unlikely to survive for long periods of time outside the host. Campylobacter spp. produce a number of enzymes that inactivate reactive oxygen intermediates, such as superoxide dismutase, alkyl hydroperoxide reductase, and catalase, and the enzymes protect the bacteria from the products of oxygen exposure. C. jejuni is susceptible to low pH, and hence, the gastric environment is sufficient to kill most campylobacters. C. jejuni can cause an enterotoxigenic-like illness with loose or watery diarrhea or an inflammatory colitis with fever and the presence of fecal blood and leukocytes and occasionally bacteremia that suggests an invasive mechanism of disease. Motility and flagella are important determinants for the invasion-translocation process. Motility mutants are frequently isolated in mutagenesis studies and point to the importance of this factor in virulence. Flagellin is an important immunogen during Campylobacter infection, and antibodies against this protein correlate to some degree with protective immunity. Several researchers are working toward developing a vaccine for Campylobacter infection. Campylobacter has received renewed attention by governmental agencies, which has already led to infusion of resources for research in the future.